Avada Kedavara is perhaps the most famous Harry Potter spell. “According to Rowling,” Mashable writes, “its root is actually Aramaic and derives from the original ‘abracadabra,’ which means ‘let the thing to be destroyed.’” That’s spooky. It also explains something about the catch-all magic phrase “abracadabra,” which was previously a minor mystery.The Mashable article is here. This spell has come up before (here, here, and here), but I don't think I have discussed it in any detail. Avada Kedavara does look like it's inspired by Abracadabra, which arguably means something like "I create according to the word" in mixed Aramaic-Hebrew. Past posts on Abracadabra are here and links.
The translation that Rowling gives for her spell is not entirely implausible. It looks to me like a mispronunciation of a Hebrew or Aramaic phrase meaning "it perished [or possibly "perish!"] according to the word," with the first word coming from the root אבד, "to perish." So the sense of being destroyed is there and the word for "word" can also mean "thing," but her grammar is very mixed up. Still, she seems to have made some effort to dig up something resembling Hebrew or Aramaic.